Overhead closures or barriers are well known and used in a variety of applications including, but not exclusively, garage doors, room dividers and the like. Most such closures are operated (i.e. opened and closed) by way of an electric motor, which is typically actuated by remote control, proximity sensors and/or by a suitable switch mounted near the closure, such as a push-button or key-pad for example.
Such closures also commonly include obstacle detection systems which prevent the closure from closing completely if an obstacle is present in its travel path. Such sensing features include a sensing edge located along the bottom edge of the closure which detects contact with such an obstacle and signals the electric motor to stop the movement of the closure and/or reverse the direction of travel thereof. Light beam based photo-switches are also used to similarly stop and reverse the closure direction in the event of an obstacle in the travel path of the closure.
However, as the closure reaches its predetermined end travel limit position (i.e. the position at which the closure is to stop in order to seal the opening closed off by the closure), such sensing features which normally reverse the direction of travel of the closure must be temporarily deactivated, so as to not undesirably re-open the closure when it is to remain closed.
Such a temporary deactivation of the sensing features is normally called the “advance close” feature of the operating device. Commonly, this is achieved mechanically using a mechanism located within the operating device which includes a two-step activation switch and a displaceable lever which acts thereon. For example, such a mechanism would operate as follows. Shortly before the closure reaches its fully closed position, the internal lever acts against a first switch to depress the actuating button thereof, thereby activating the advance close feature (i.e. temporarily deactivating the sensing features) such as to prevent the sensors from inopportunely reversing the door travel direction upon reaching the fully closed position. Once the closure reaches its “advance close” position, the lever is further displaced to depress a second switch that requires greater actuating button travel, i.e. in order to thereby fully stop all movement of the closure. Alternately, a single stop switch may be used, which has a two-tiered stop button travel. Typically, the displaceable lever is acted upon by a cam disk which translates along an endless screw within the operating device in accordance with the position of the closure.
One problem with the above-described mechanically operated advance close feature typical of most closure operating devices resides in the lack of adjustability and control that they provide. Further, they necessitate careful setup and make adjusting the full stop position of the closure, and particularly fine tuning the advance close position thereof, difficult. For instance, if the device has been configured to be installed within an opening such that the closure will travel at a given speed, but an alternate speed, and therefore location of the deactivation of the sensing features, is in fact required, careful readjustment of the relative positions of the lever and cam disk location of the mechanism within the operating device must be performed. Further, this also necessitates a relatively complex two-stage switch used to stop the electric motor driving the closure.
An improved closure operating device is therefore sought.